Update CMakeFiles, add initial pair potential implementation and tests

src/CMakeLists.txt

@@ -1,4 +1,4 @@
-project(${CMAKE_PROJECT_NAME}_lib CUDA CXX)
+project(${NAME}_lib CUDA CXX)
 
 set(HEADER_FILES
     particle.hpp
@@ -11,7 +11,7 @@ set(SOURCE_FILES
 )
 
 # The library contains header and source files.
-add_library(${CMAKE_PROJECT_NAME}_lib 
+add_library(${NAME}_lib 
     ${HEADER_FILES} 
     ${SOURCE_FILES}
 )

src/pair_potentials.cpp

@@ -1,6 +1,7 @@
-#include "potentials.hpp"
+#include "pair_potentials.hpp"
 #include <cmath>
 
+PairPotential::~PairPotential() {};
 /**
  * Calculate the Lennard-Jones energy and force for the current particle pair
  * described by displacement vector r
@@ -12,17 +13,16 @@ ForceAndEnergy LennardJones::calc_force_and_energy(Vec3<real> r) {
 
     // Pre-Compute the terms (doing this saves on multiple devisions/pow
     // function call)
-    real sigma_r = m_sigma / inv_rmag;
-    real sigma_r5 = sigma_r * sigma_r * sigma_r * sigma_r * sigma_r;
-    real sigma_r6 = sigma_r5 * sigma_r;
-    real sigma_r11 = sigma_r5 * sigma_r5 * sigma_r;
+    real sigma_r = m_sigma * inv_rmag;
+    real sigma_r6 = sigma_r * sigma_r * sigma_r * sigma_r * sigma_r * sigma_r;
     real sigma_r12 = sigma_r6 * sigma_r6;
 
     // Get the energy
     real energy = 4.0 * m_epsilon * (sigma_r12 - sigma_r6);
 
     // Get the force vector
-    real force_mag = 4.0 * m_epsilon * (6.0 * sigma_r5 - 12.0 * sigma_r11);
+    real force_mag = 4.0 * m_epsilon *
+                     (12.0 * sigma_r12 * inv_rmag - 6.0 * sigma_r6 * inv_rmag);
     Vec3<real> force = r.scale(force_mag * inv_rmag);
 
     return {energy, force};

src/pair_potentials.hpp

@@ -24,6 +24,9 @@ struct ForceAndEnergy {
 struct PairPotential {
   real m_rcutoffsq;
 
+  PairPotential(real rcutoff) : m_rcutoffsq(rcutoff * rcutoff) {};
+  virtual ~PairPotential() = 0;
+
   /**
    * Calculate the force and energy for a specific atom pair based on a
    * displacement vector r.
@@ -35,7 +38,12 @@ struct LennardJones : PairPotential {
   real m_epsilon;
   real m_sigma;
 
+  LennardJones(real sigma, real epsilon, real rcutoff)
+      : PairPotential(rcutoff), m_epsilon(epsilon), m_sigma(sigma) {};
+
   ForceAndEnergy calc_force_and_energy(Vec3<real> r);
+
+  ~LennardJones() {};
 };
 
 #endif